Three-dimensional nanostructures and method for fabricating the same

ABSTRACT

A three-dimensional nanostructures and a method for fabricating the same, and more particularly to three-dimensional structures of various shapes having high aspect ratio and uniformity in large area and a method of fabricating the same by attaching a target material to the outer surface of patterned polymer structures using an ion bombardment phenomenon occurring during a physical ion etching process to form target material-polymer composite structures, and then removing the polymer from the target material-polymer structures. A three-dimensional nanostructures with high aspect ratio and uniformity can be fabricated by a simple process at low cost by using the ion bombardment phenomenon occurring during physical ion etching. Also, nanostructures of various shapes can be easily fabricated by controlling the pattern and shape of polymer structures. In addition, uniform fine nanostructures having a thickness of 10 nm or less can be formed in a large area.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. application Ser.No. 13/081,276, filed Apr. 6, 2011 now U.S. Pat. No. 8,889,245, thedisclosure of which is incorporated herein by reference. Thisapplication claims priority benefits under 35 U.S.C. §1.119 to KoreanPatent Application No. 10-2010-0062183 filed Jun. 29, 2010.

TECHNICAL FIELD

The present invention relates to three-dimensional nanostructures and amethod for fabricating the same, and more particularly tothree-dimensional structures of various shapes having high aspect ratioand uniformity in large area and a method of fabricating the same byattaching a target material to the outer surface of patterned polymerstructures using an ion bombardment phenomenon occurring during aphysical ion etching process to form target material-polymer compositestructures, and then removing the polymer from the targetmaterial-polymer structures.

BACKGROUND ART

In recent years, with the tendency for increased integration andminiaturization of electronic devices, studies on nanostructuredmaterials and fabrication methods thereof have been very activelyconducted.

Particularly, it is thought that techniques for fabricating large-areananopatterns of high resolution and high aspect ratio are necessary toachieve the high performance of future nano-devices, such as nanosizedelectronic devices, optical devices, bio-devices and energy devices.Also, nanoimprint, e-beam, dip-pen, block copolymer and soft lithographytechniques have been studied to realize high-performance nano-devices.

The dip-pen, e-beam and scanning probe microscope (SPM) lithographytechniques capable of showing the highest resolution have an advantagecapable of fabricating high-resolution patterns on the order of tens ofnanometers, but suffer from a disadvantage in that they havesignificantly slow processing speeds, because they involve scanning witha tip. In addition, these techniques have to use expensive equipmentthat limit the actual use of these techniques in research andproduction.

Also, the nanoimprint and soft lithography techniques capable offabricating nanopatterns in large area within a relatively short processtime have an advantage in that a pattern having the size of a mask moldcan be repeatedly transferred to a large-area substrate, but suffer fromlimitations in that it is impossible to fabricate a pattern having asize smaller than that of the mask mold and in that it is very expensiveto fabricate a mask of less than 100 nm. Moreover, in these lithographytechniques, because a pattern is fabricated using a stamping or etchingprocess, only the two-dimensional shape of the mask mold is transferredas it is, and thus it is impossible to fabricate a three-dimensionalpattern. In addition, when nanostructured patterns of other sizes orshapes are to be fabricated, other mask molds should be fabricated.

Accordingly, the present inventors have made many efforts to solve theabove-mentioned problems occurring in the prior art and, as a result,have found that three-dimensional nanostructures of various shapeshaving high aspect ratio and uniformity can be fabricated by attaching atarget material to the outer surface of patterned polymer structuresusing an ion bombardment phenomenon occurring during an ion etchingprocess to form target material-polymer composite structures, and thenremoving the polymer from the target material-polymer compositestructures, thereby completing the present invention.

DISCLOSURE OF INVENTION

It is a main object of the present invention to providethree-dimensional nanostructures of various shapes having high aspectratio and uniformity and a fabrication method thereof.

To achieve the above object, the present invention provides a method forfabricating three-dimensional nanostructures, the method including thesteps of: (a) forming a target material layer and a polymer layersequentially on a substrate; (b) performing a lithography process on thepolymer layer to form patterned polymer structures; (c) ion-etching thetarget material layer to form target material-polymer compositestructures including the ion-etched target material attached to theouter surface of the polymer structures; and (d) removing the polymerfrom the target material-polymer composite structures, therebyfabricating three-dimensional nanostructures. The present invention alsoprovides three-dimensional nanostructures which are fabricated by saidmethod and have a shape selected from the group consisting of acylindrical shape, an inverse conical shape, a rectangularparallelepiped shape, a line shape, a “

” shape and a top shape.

The present invention also provides a method for fabricatingthree-dimensional nanostructures, the method including the steps of: (a)forming a polymer layer on a substrate, and patterning the formedpolymer layer by a lithography process to form patterned polymerstructures; (b) forming a target material layer on the substrate havingthe patterned polymer structures formed thereon; (c) ion-etching thetarget material layer to form target material-polymer compositestructures including the ion-etched target material attached to theouter surface of the polymer structures; (d) removing the polymer fromthe target material-polymer composite structures, thereby fabricating athree-dimensional nanostructure. The present invention also providesthree-dimensional nanostructures which are fabricated by said method andhave a shape selected from the group consisting of a cylindrical shape,an inverse conical shape, a rectangular parallelepiped shape, a lineshape, a “

” shape and a top shape.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will be more clearly understood from the following detaileddescription taken in conjunction with the accompanying drawing, inwhich:

FIG. 1 shows a process for fabricating three-dimensional nanostructuresaccording to one embodiment of the present invention;

FIG. 2 depicts scanning electron micrographs of three-dimensionalnanostructures fabricated according to one embodiment of the presentinvention;

FIG. 3 is a schematic view showing an ion etching process according tothe present invention;

FIG. 4 shows a process for fabricating three-dimensional nanostructuresaccording to another embodiment of the present invention;

FIG. 5 shows a process for fabricating three-dimensional nanostructuresof rectangular parallelepiped shape according to the present invention;

FIG. 6 depicts scanning electron micrographs of three-dimensionalnanostructures of rectangular parallelepiped shape according to thepresent invention (a: three-dimensional gold nanostructures; b:three-dimensional platinum structures; c: three-dimensional zinc oxidenanostructures; and d: three-dimensional aluminum nanostructures);

FIG. 7 shows a process for fabricating three-dimensional nanostructuresof top shape according to the present invention (a) and a scanningelectron micrograph of the three-dimensional nanostructures of top shape(b);

FIG. 8 shows a process for fabricating three-dimensional nanostructuresof conical shape according to the present invention (a) and a scanningelectron micrograph of the three-dimensional nanostructures of conicalshape (b); and

FIG. 9 shows scanning electron micrographs of three-dimensionalnanostructures fabricated according to another embodiment of the presentinvention (a: PS structures having a 520-nm height; b: three-dimensionalgold nanostructures having a 500-nm height; c: PS structures having a120-nm height; and d: three-dimensional gold nanostructures having a100-nm height).

BEST MODE FOR CARRYING OUT THE INVENTION

In one aspect, the present invention is directed to a method forfabricating three-dimensional nanostructures, the method including thesteps of: (a) forming a target material layer and a polymer layersequentially on a substrate; (b) performing a lithography process on thepolymer layer to form patterned polymer structures; (c) ion-etching thetarget material layer to form target material-polymer compositestructures including the ion-etched target material attached to theouter surface of the polymer structures; and (d) removing the polymerfrom the target material-polymer composite structures, therebyfabricating three-dimensional nano structures.

The key idea of the present invention is to use an ion bombardmentphenomenon in which particles of a physically bombarded target materialare scattered in all directions. According to the present invention,three-dimensional nanostructures with high aspect ratio and uniformityare fabricated in large area by providing patterned polymer structureshaving an outer surface to which target material particles scatteredfrom a target material layer can be attached, and then removing only thepolymer from target material-polymer composite structures formed as aresult of a process in which the particles scattered from the targetmaterial by the ion bombardment phenomenon are attached to polymerstructures.

FIG. 1 and FIG. 2 show a method for fabricating three-dimensionalnanostructures according to the present invention. As shown therein, atarget material and a polymer are sequentially applied to a substrate110 to form a target material layer 120 and a polymer layer 130 on thesubstrate 110 (FIG. 1( a)).

The substrate 110 is a flat plate and may be made of any material thatdoes not undergo physical deformation caused by the temperature andpressure of a lithography process. Preferably, the substrate 110 is madeof a material selected from the group consisting of silicon, siliconoxide, quartz, glass, polymers, and mixtures thereof.

As used herein, the term “target material” means a material constitutingthe three-nanostructure nanostructures that are final products. Thetarget material is a polycrystalline material which can be scattered inall directions by the ion bombardment phenomenon occurring duringphysical ion etching as described below. Preferably, the target materialis selected from the group consisting of gold, platinum, silver, copper,aluminum, zinc oxide, chromium, silicon dioxide, indium tin oxide, andmixtures thereof.

The polymer that is used in the present invention may be any polymerthat can be used in a lithography process. Preferably, the polymer isselected from the group consisting of polystyrene, chitosan, polyvinylalcohol, polymethylmethacrylate (PMMA), and mixtures thereof.

In the present invention, in the process of forming the target materiallayer 120 and the polymer layer 130 sequentially on the substrate 110,the target material layer 120 is generally formed by a process selectedfrom the group consisting of chemical vapor deposition (CVD), atomiclayer deposition, sputtering, laser ablation, arc discharge, plasmadeposition, thermal chemical vapor deposition and e-beam evaporationprocesses, and the polymer layer 130 is formed by spin coating or spraycoating.

In the present invention, the target material layer 120 may be formed tohave a multilayer structure depending on the intended use or the like ofthe three-dimensional nanostructures that are final products.

The polymer layer 130 formed on the target material layer 120 asdescribed above is patterned by a lithography process (FIG. 1( b)) usinga nanoimprint mold 140, thereby forming patterned polymer structures 135(FIGS. 1( c) and 2(a)). Because the shape of the formed polymerstructures 135 determines the shape of three-dimensional nanostructuresto be fabricated, three-dimensional nanostructures 200 of various shapescan be easily fabricated by controlling the shape of the polymerstructures 135 using various lithography processes.

The lithography process that is used in the present invention may be aconventional lithography process. Preferably, it is carried out by atleast one process selected from the group consisting of nanoimprintlithography, soft lithography, block copolymer lithography,photolithography and capillary lithography.

In the present invention, target material-polymer composite structures150 are formed by attaching particles of a target material 125 to theouter surface of the polymer structures 135, formed as described above,using an ion bombardment phenomenon occurring during physical ionetching of the target material (FIGS. 1( d) and 2(b)).

As shown in FIG. 3, the ion bombardment phenomenon refers to aphenomenon in which, when ions (e.g., argon ions) accelerated by avoltage difference are physically bombarded onto the target materiallayer 120, particles of the bombarded target material 125 are scatteredin the crystal direction due to high-energy bombardment.

In the present invention, as a physical ion etching process for creatingthe ion bombardment phenomenon, ion milling is carried out.

Where the ion bombardment phenomenon is created by applying high energyto small ions, the wide angle distribution of the polycrystallineorientation becomes narrower to reduce the angle at which the particlesare scattered, thus making it difficult to attach the particles of thetarget material 125 to the outer surface of the patterned polymerstructures 135. For this reason, the physical ion etching process ispreferably carried out by forming plasma using a heavy gas such as argonunder a process pressure of 0.1-10 mTorr, and then accelerating theplasma in the range of 200-1,000 eV.

In the physical etching process, if ion etching is carried out usingplasma accelerated to more than 1,000 eV, particles will be scatteredfrom the target material layer in the vertical direction equal to theion incidence direction, and thus the amount of particles attached tothe outer surface of the polymer structures will be small. On the otherhand, if ion etching is carried out using plasma accelerated in therange of less than 200 eV, the etching rate of the target material layerwill be low, and thus the operating efficiency will be low.

In the present invention, the heavy gas is selected from the groupconsisting of argon, helium, nitrogen, hydrogen, oxygen, and mixturesthereof. Preferably, it is argon.

The target material-polymer composite structures 150 formed as describedabove are dry-etched or wet-etched to remove the polymer 135, therebyfabricating three-dimensional nanostructures 200 (FIGS. 1( e) and 2(c)).The dry etching or wet etching is carried out by a conventional etchingprocess capable of removing the polymer.

In the method for fabricating three-dimensional nanostructures accordingto the present invention, only desired patterned three-dimensionalnanostructures can be fabricated by fabricating the three-dimensionalnanostructures 200, and then removing an unnecessary target materialportion from the fabricated three-dimensional nanostructures 200 by ionetching.

In the method for fabricating three-dimensional nanostructures accordingto the present invention, there-dimensional nanostructures with highaspect ratio and uniformity can be fabricated in large area by a simpleprocess at low cost by using the ion bombardment phenomenon occurringduring physical ion etching. Also, various structures can be easilyfabricated by controlling the pattern of the polymer structures, anduniform fine nanostructures having a thickness of 10 nm or less can beformed in a large area.

In another aspect, the present invention is also directed tothree-dimensional nanostructures which are fabricated by said method andhave a shape selected from the group consisting of a cylindrical shape,an inverse conical shape, a rectangular parallelepiped shape, a lineshape, a “

” shape and a top shape. The three-dimensional nanostructures contain apolycrystalline material in which the ion bombardment phenomenon occurswell and have an aspect ratio of 50 or less.

According to the present invention, three-dimensional nanostructureshaving a high height of 500 nm or more can be uniformly fabricated in alarge area by ion-etching a target material layer having a smallthickness ranging from 20 nm to 30 nm. Thus, the surface area of thethree-dimensional nanostructures can be increased, and the height of thenanostructures can be easily controlled by additional etching, thuscontrolling the increase in the surface area. Also, because thethree-dimensional nanostructures have high aspect ratio, they can bewidely used in optical studies on patterns having high aspect ratio.

In another aspect, the present invention is directed to a method forfabricating three-dimensional nanostructures, the method including thesteps of: (a) forming a polymer layer on a substrate, and patterning theformed polymer layer by a lithography process to form patterned polymerstructures; (b) forming a target material layer on the substrate havingthe patterned polymer structures formed thereon; (c) ion-etching thetarget material layer to form target material-polymer compositestructures including the ion-etched target material attached to theouter surface of the polymer structures; and (d) removing the polymerfrom the target material-polymer composite structures, therebyfabricating three-dimensional nanostructures.

As shown in FIG. 4, the method for manufacturing three-dimensionalnanostructures according to the present invention comprises applying apolymer layer 130 to a substrate 110 (FIG. 4( a)), and then formingpatterned polymer structures 135 by a lithography process (FIG. 4( b)).A target material layer 120 is formed on the substrate having thepatterned polymer structures 135 formed thereon (FIG. 4( c)), and theformed target material layer 120 is physically ion-etched so that thetarget material particles are attached to the outer surface of thepolymer structures 135 by the ion bombardment phenomenon, therebyforming target material-polymer structures 150 (FIG. 4( d)). Only thepolymer 135 is removed from the formed target material-polymerstructures 150, thereby fabricating three-dimensional nanostructures(FIG. 4( e)).

This fabrication method has a advantage in that a step of removing thetarget material 125 excluding the three-dimensional nanostructures 200after fabricating the three-dimensional nanostructures 200 does not needto be carried out.

In still another aspect, the present invention is directed topolycrystalline material-containing three-dimensional nanostructureswhich are fabricated by said method and the shape of which is controlledaccording to the shape of the outer surface of the polymer structuresand which have an aspect ratio of 25 or less.

The three-dimensional structures according to the present invention arefabricated using the ion bombardment phenomenon in which particles ofthe physically bombarded target material are scattered in alldirections. Namely, the three-dimensional structures are fabricated byproviding patterned polymer structures to which target materialparticles scattered by the ion bombardment phenomenon can be attached,and then removing the polymer to which the target material particles hadbeen attached. Thus, the shape of the nanostructures can be easilycontrolled according to the shape of the outer surface of the polymerstructures, and the nanostructures having high aspect ratio anduniformity are formed in a large area.

EXAMPLE

Hereinafter, the present invention will be described in further detailwith reference to examples. It will be obvious to a person of ordinaryskill in the art that these examples are illustrative purposes only andare not to be construed to limit the scope of the present invention.

Example 1 Fabrication of Three-Dimensional Nanostructures of CylindricalShape

1-1: Formation of Polymer Structures

Gold was deposited on a glass substrate to a thickness of 15 nm bye-beam evaporation, and then a polystyrene (3 wt %)/toluene mixture wasspin-coated thereon, after which the toluene was evaporated to form apolystyrene layer having a 135-nm thickness. The formed polystyrenelayer was patterned using a nanoimprint mold having depressions ofcylindrical shape at 135° C. in a vacuum under capillary force for 1hour, whereby polystyrene patterns of cylindrical shape having an outerdiameter of 500 nm, a height of 550 nm and an interval between polymerstructures of 900 nm were formed in an area of 7 mm×7 mm. Then, thenanoimprint mold was detached, and the remaining structures were cooled,thereby forming patterned polystyrene structures. The polystyrene layerexcluding the formed polystyrene structures was removed by reactive ionetching using a mixed gas of oxygen and tetrafluoromethane (40:60),whereby polystyrene structures having an outer diameter of 400 nm, aheight of 500 nm and an interval between structures of 1000 nm wereformed on the glass substrate (FIG. 2( a)).

1-2: Formation of Target Material-Polymer Composite Structures

The gold layer on which the patterned polystyrene structures had beenformed as described in Example 1-1 above was ion-etched in an ionmilling system (VTS Co., Ltd., Korea) using plasma, formed from argongas, under a pressure of 0.1 mTorr at 500 eV, thereby forminggold-polystyrene composite structures including gold particles attachedto the outer surface of the polystyrene structures (FIG. 2( b)).

1-3: Fabrication of Three-Dimensional Nanostructures

The gold-polystyrene composite structures formed in Example 1-2 abovewere reactive-ion etched under an oxygen atmosphere and sonicated in adichoromethane solution to remove the polystyrene, thereby fabricatingthree-dimensional gold nanostructures of hollow cylindrical shape havingan outer diameter of 400 nm, an inner diameter of 385 nm, a thickness of15 nm and a height of 500 nm (FIG. 2( c)).

Example 2 Fabrication of Three-Dimensional Nanostructures of RectangularParallelepiped Shape/Line Shape

According to the same method as described in Example 1,three-dimensional gold nanostructures of “

” shape having a size of 5 mm (length)×250 nm (height)×500 nm (width)and a thickness of 15 nm (FIG. 6( a)), three-dimensional platinumnanostructures of “

” shape having a size of 5 mm (length)×150 nm (height)×500 nm (width)and a thickness of 15 nm (FIG. 6( b)), three-dimensional zinc oxidenanostructures of “

” shape having a size of 5 mm (length)×85 nm (height)×500 nm (width) anda thickness of 15 nm, and three-dimensional nanostructures of “

” shape having a size of 5 mm (length)×100 nm (height)×500 nm (width)and a thickness of 15 nm were fabricated using a nanoimprint mold,having depressions of rectangular parallelepiped shape as shown in FIG.5, and using gold, platinum, zinc oxide or aluminum as a targetmaterial. In addition, the three-dimensional zinc oxide nanostructuresand the three-dimensional aluminum nanostructures were further treatedby ion milling, thereby fabricating three-dimensional zinc oxidenanostructures of line shape having a size of 5 mm (length)×85 nm(height)×500 nm (width) and a thickness of 15 nm (FIG. 6( c)), andthree-dimensional aluminum nanostructures having a size of 5 mm(length)×100 nm (height)×500 nm (width) and a thickness of 15 nm (FIG.6( d)).

Example 3 Fabrication of Three-Dimensional Nanostructures of Top Shape

According to the same method as described in Example 1, patternedpolystyrene structures were formed using a nanoimprint mold havingdepressions of cylindrical shape as shown in FIG. 2. The lower portionof the patterned polystyrene structures was over-etched by reactive ionetching using a mixed gas of oxygen and tetrafluoromethane (40:60) undera low vacuum of 0.1 Torr, after which three-dimensional goldnanostructures of top shape were fabricated using the polystyrenestructures (FIG. 7( a)).

As a result, as can be seen in FIG. 7( b), three-dimensional goldnanostructures of hollow top shape having a maximum outer diameter of300 nm, a minimum outer diameter of 250 nm and a height of 200 nm werefabricated.

Example 4 Fabrication of Three-Dimensional Nanostructures of InverseConical Shape

According to the same method as described in Example 1, patternedpolystyrene structures were formed using a nanoimplant mold havingdepressions of inverse conical shape, after which three-dimensional goldnanostructures of hollow inverse conical shape were formed using thepolystyrene structures (FIG. 8( a)).

As a result, as can be seen in FIG. 8( b), three-dimensional goldnanostructures of hollow conical shape having an outer diameter of 250nm and a height of 150 nm were fabricated.

Example 5 Fabrication of Nanostructures According to Another Embodiment

2-1: Formation of Polymer Structures

A polystyrene/toluene mixture was spin-coated on a glass substrate, andthen the toluene was evaporated, thus forming a polystyrene layer havinga thickness of 135 nm. The formed polystyrene layer was patterned usinga nanoimprint mold, having depressions of cylindrical shape, at 135° C.under capillary force for 1 hour in a vacuum. Then, the nanoimprint moldwas detached, and the remaining structures were cooled, thereby formingpatterned polystyrene structures.

2-2: Formation of Target Material-Polymer Composite Structures

On the glass substrate having the polystyrene structures formed thereonas described in Example 2-1 above, gold was deposited to a thickness of15 nm by e-beam evaporation, thereby forming a gold layer on thepolystyrene structures. The gold layer was ion-etched in an ion millingsystem (VTS Co., Ltd., USA) using plasma, formed from argon gas, under apressure of 0.1 mTorr at 500 eV, thereby forming gold-polystyrenecomposite structures including gold particles attached to the outersurface of the polystyrene structures.

3-3: Fabrication of Three-Dimensional Nanostructures

The gold-polystyrene composite structures fabricated in Example 2-2above were subjected to reactive ion etching under an oxygen atmosphere,and then sonicated in a dichloromethane solution to remove thepolystyrene, thereby fabricating three-dimensional nanostructures ofhollow cylindrical shape having an outer diameter of 400 nm, an innerdiameter of 385 nm and a height of 500 nm.

Example 6 Fabrication of Nanostructures According to Another Embodiment

According to the same method as described in Example 1, patternedpolystyrene structures of cylindrical shape having a height of 500 nmwere fabricated (FIG. 9( a)), after which three-dimensional goldnanostructures having a height of 500 nm were fabricated using thepatterned polystyrene structures (FIG. 9( b)).

Also, the patterned polystyrene structures having a height of 500 nm(FIG. 9( a)) were reactive-ion-etched with a mixed gas of oxygen andtertrafluoromethane (40:60) under a high vacuum (0.001 Torr) for 2minutes to form patterned polystyrene structures of cylindrical shapehaving a height of 100 nm (FIG. 9( c)), after which three-dimensionalgold nanostructures having a height of 100 nm (FIG. 9( d)) werefabricated according to the same method as Example 1 using the patternedpolystyrene structures.

As a result, it could be seen that the pattern height of the targetmaterial could be controlled by controlling the height of the polymerstructures.

Although the present invention has been described in detail withreference to the specific features, it will be apparent to those skilledin the art that this description is only for a preferred embodiment anddoes not limit the scope of the present invention. Thus, the substantialscope of the present invention will be defined by the appended claimsand equivalents thereof.

INDUSTRIAL APPLICABILITY

As described above, according to the method of the present invention,three-dimensional nanostructures with high aspect ratio and uniformitycan be fabricated by a simple process at low cost by using the ionbombardment phenomenon occurring during physical ion etching. Also,nanostructures of various shapes can be easily fabricated by controllingthe pattern and shape of polymer structures. In addition, uniform finenanostructures having a thickness of 10 nm or less can be formed in alarge area. Accordingly, the present invention can achieve the highperformance of future nano-devices, such as nanosized electronicdevices, optical devices, bio-devices and energy devices.

EXPLANATION ON REFERENCE NUMERALS OF MAIN ELEMENTS

110: substrate 120: target material layer

125: target material 130: polymer layer

135: polymer 140: nanoimprint mold

150: target material-polymer composite structures

200: three-dimensional nanostructures

What is claimed is:
 1. A method for fabricating three-dimensionalnanostructures, comprising the steps of: (a) forming a target materiallayer and a polymer layer sequentially on a substrate; (b) performing alithography process on the polymer layer to form patterned polymerstructures; (c) ion-etching the target material layer to form targetmaterial-polymer composite structures including the ion-etched targetmaterial attached to the outer surface of the polymer structures; and(d) removing the polymer from the target material-polymer compositestructures, thereby fabricating three-dimensional nanostructures,wherein the three-dimensional nanostructures comprises a pattern oftarget material having a hollow shape selected from the group consistingof a cylindrical shape, an inverse conical shape, a rectangularparallelepiped shape, a top shape, a line shape and a “

” shape, and having an aspect ratio of 50 or less.
 2. The method forfabricating three-dimensional nanostructures according to claim 1,wherein the target material is a polycrystalline material.
 3. The methodfor fabricating three-dimensional nanostructures according to claim 2,wherein the target material is selected from the group consisting ofgold, platinum, silver, copper, aluminum, zinc oxide, chromium, silicondioxide, indium tin oxide, and mixtures thereof.
 4. The method forfabricating three-dimensional nanostructures according to claim 1,wherein the substrate is selected from the group consisting of silicon,silicon oxide, quartz, glass, polymers, and mixtures thereof.
 5. Themethod for fabricating three-dimensional nanostructures according toclaim 1, wherein the polymer is selected from the group consisting ofpolystyrene, chitosan, polymethylmethacrylate, polyvinyl alcohol, andmixtures thereof.
 6. The method for fabricating three-dimensionalnanostructures according to claim 1, wherein the lithography process inthe step of (b) is carried out by at least one process selected from thegroup consisting of nanoimprint lithography, soft lithography,photolithography, block copolymer lithography and capillary lithography.7. The method for fabricating three-dimensional nanostructures accordingto claim 1, wherein the ion etching process in the step of (c) iscarried out by ion milling.
 8. The method for fabricatingthree-dimensional nanostructures according to claim 7, wherein the ionmilling is carried out by forming plasma using a gas under a processpressure of 0.1-10 mTorr, and then accelerating the plasma in the rangeof 200-1,000 eV.
 9. The method for fabricating three-dimensionalnanostructures according to claim 8, wherein the gas is selected fromthe group consisting of argon, helium, nitrogen, oxygen, and mixturesthereof.
 10. The method for fabricating three-dimensional nanostructuresaccording to claim 1, wherein the removal of the polymer in the step of(d) is carried out by a dry etching or wet etching process.
 11. A methodfor fabricating three-dimensional nanostructures, comprising the stepsof: (a) forming a polymer layer on a substrate, and then performing alithography process to form patterned polymer structures; (b) forming atarget material layer on the substrate having the patterned polymerstructures formed thereon; (c) ion-etching the target material layer toform target material-polymer composite structures including theion-etched target material attached to the outer surface of the polymerstructures; (d) removing the polymer from the target material-polymercomposite structures, thereby fabricating a three-dimensionalnanostructure, wherein the three-dimensional nanostructures comprising apattern of target material having a hollow shape selected from the groupconsisting of a cylindrical shape, an inverse conical shape, arectangular parallelepiped shape, a top shape, a line shape and a “

” shape, and having an aspect ratio of 50 or less.
 12. The method forfabricating three-dimensional nanostructures according to claim 11,wherein the target material is a polycrystalline material.
 13. Themethod for fabricating three-dimensional nanostructures according toclaim 11, wherein the target material is selected from the groupconsisting of gold, platinum, silver, copper, aluminum, zinc oxide,chromium, silicon dioxide, indium tin oxide, and mixtures thereof. 14.The method for fabricating three-dimensional nanostructures according toclaim 11, wherein the substrate is selected from the group consisting ofsilicon, silicon oxide, quartz, glass, polymers, and mixtures thereof.15. The method for fabricating three-dimensional nanostructuresaccording to claim 11, wherein the polymer is selected from the groupconsisting of polystyrene, chitosan, polymethylmethacrylate, polyvinylalcohol, and mixtures thereof.
 16. The method for fabricatingthree-dimensional nanostructures according to claim 11, wherein thelithography process in the step of (a) is carried out by at least oneprocess selected from the group consisting of nanoimprint lithography,soft lithography, photolithography, block copolymer lithography andcapillary lithography.
 17. The method for fabricating three-dimensionalnanostructures according to claim 11, wherein the ion etching process inthe step of (c) is carried out by ion milling.
 18. The method forfabricating three-dimensional nanostructures according to claim 17,wherein the ion milling is carried out by forming plasma using a gasunder a process pressure of 0.1-10 mTorr, and then accelerating theplasma in the range of 200-1,000 eV.
 19. The method for fabricatingthree-dimensional nanostructures according to claim 18, wherein the gasis selected from the group consisting of argon, helium, nitrogen,oxygen, and mixtures thereof.
 20. The method for fabricatingthree-dimensional nanostructures according to claim 13, wherein theremoval of the polymer in the step of (d) is carried out by a dryetching or wet etching process.